An alpha particle is:
a hydrogen atom
a nucleus of helium
two neutrons
an electron

a nucleus of helium

Explanation:

An alpha particle is a positively charged nucleus of a HELIUM-4 atom (consisting of two protons and two neutrons), emitted as a consequence of radioactivity;

It can be written as α-particle.

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nucleic acid molecules are incredibly complex, containing the code that guarantees the four different nucleotide units comprise dna, the nucleic acid of interest to the genealogist. and one of four nitrogen-containing molecules called nucleotides